Large concrete delivery trucks with rotating (spinning) drums which can accommodate 9-11 yards or even more of concrete are well known. In operation, it is important that the drum be kept spinning, regardless of whether the truck is moving or at a standstill. This maintains the concrete within the drum in a desired mix state.
In order to accomplish this, power for the spinning drum on the large concrete trucks is taken from the engine flywheel. In this arrangement, the drum continues to spin as long as the engine is running.
Small-load concrete trucks, e.g. those trucks having a 2-5 cubic yard capacity, also have used flywheel take-off systems to provide power for spinning of the drum. However, this arrangement has some disadvantages for smaller or medium-sized commercial trucks which are not specifically manufactured to carry concrete drums. Hence, it is desirable for a concrete truck with a small load drum to have a power system which does not use the engine flywheel and which spins the concrete drum as long as the engine is running.